The top US envoy to the United Nations and Foreign Minister Cho Tae-yul discussed ways to build a new mechanism for monitoring the enforcement of UN sanctions on North Korea, Cho's office said Monday, after Russia vetoed a resolution meant to renew the monitoring mandate.

The meeting between Cho and Ambassador Linda Thomas-Greenfield came amid growing concerns that Moscow's rejection to extend the mandate for the UN Panel of Experts on North Korean sanctions could undermine international efforts to monitor violations of sanctions imposed on Pyongyang over its illicit weapons programs.

Thomas-Greenfield arrived in Seoul on Sunday on a four-day trip as part of an Asia swing that will also take her to Japan.

"Minister Cho and Amb. Thomas-Greenfield expressed deep disappointment that the bid to extend the expert panel under the UN sanctions committee on North Korea was thwarted due to Russia's veto," the ministry said in a release.

"They discussed various ways to establish a new mechanism to monitor the implementation of sanctions against North Korea," it said.

In a separate readout, US Mission to the UN spokesperson Nate Evans said that Cho and Thomas-Greenfield talked about the "next steps to ensure a continuation of independent and accurate reporting" of the North's ongoing weapons of mass destruction and ballistic missile advancements and sanctions evasion activities, following Russia's veto.

As an elected member of the UN Security Council for 2024-25, Cho expressed hope that South Korea will use the platform to deepen trilateral cooperation with the United States and Japan in responding to pending global issues at the UNSC level, according to the foreign ministry.

Thomas-Greenfield also suggested capitalizing on this occasion in which South Korea and Japan are both serving on the UNSC as nonpermanent members, noting how the elected members like South Korea played an important role in the successful adoption of the resolution calling for a ceasefire in the Gaza Strip.

Cho asked for Washington's attention on the human rights situations in North Korea and North Korean escapees. Thomas-Greenfield reaffirmed the importance of the three-way cooperation involving Japan to increase the visibility of the issue within the UN

Iran's attack on Israel, the security situation in the Gaza Strip amid the ongoing conflict between Israel and the Hamas group, and efforts to expand humanitarian assistance in this region were also among what was discussed at Monday's meeting, Cho's office said.

Later Monday, the US envoy met with Defense Minister Shin Won-sik and expressed concern over Russia's recent veto, noting that it could create lapses in implementing UN Security Council sanctions resolutions on the North, according to Seoul's defense ministry.

The US envoy explained that Washington is making efforts to ensure that an alternative credible report on North Korean sanctions can continue to be produced, and expressed hopes for support from South Korea, it said.

The US envoy called North Korea's advancement of its nuclear and ballistic missile programs violations of UN Security Council resolutions, and an illegal act that undermines the universal values of the international community.

The two sides also expressed concern over increasing uncertainty in the global security situation, and agreed to cooperate to push for projects connected to the UN Security Council resolutions, according to the ministry.

Her visit came after Russia last month vetoed the UN's annual renewal of an expert panel monitoring the North's compliance with UN sanctions.

North Korea has been under tightened UN sanctions, which call for, among other things, a ban on the country's exports of coal and other mineral resources to cut off North Korea's access to hard currency.

With the veto, the panel's mandate is set to expire April 30, a termination that observers say could chip away at international efforts to curb evolving North Korean nuclear and missile threats.

During her trip, the US envoy will also travel to the Demilitarized Zone separating the two Koreas, meet young North Korean defectors and speak with students at Ewha Womans University before heading to Japan on Wednesday.

It marks Thomas-Greenfield's first visit to Seoul, and the first trip by a US ambassador to the UN since 2016. (Yonhap)